Is Signal App Killing My iPhone Battery?

I have been trying to find the culprit of the excessive battery consumption of my iPhone (SE 2022, running iOS 16.5.1).

After comings and goings that included a heated conversation with Apple support, I noticed that Signal may be the one to blame.

Before detailing the situation, I share this screenshot showing the absurd consumption of the battery, phone untouched, of ~80% overnight:

What led me to Signal was the fact that the application appears frequently among those who use the most battery, thanks to the background activity.

Apple support had recommended force closing messaging apps, such as WhatsApp. I’ve never done this with any of my three previous iPhones, but I did the experiment with Signal and WhatsApp, the two messaging apps left on the phone. And… it fixed the issue?

iPhone battery drain problems by Signal are not uncommon — on the official forum, on Reddit, on GitHub, and a more recent issue marked as “stale” — and date back to 2017. In one of the posts, someone suggests that disabling notifications solves the problem. I haven’t tried that yet.

Anyway, I uploaded a debug file on the more recent issue on GitHub.

On a related note, a very curious phenomenon is happening with WhatsApp.

I disabled all updates in the background, in an unsuccessful attempt to mitigate excessive battery consumption. Still, WhatsApp can spend 2 minutes of battery per hour doing… updates in the background.

According to NextDNS, every 5~10 minutes the cell phone “ping” the domain “g.whatsapp.net”, even without me opening WhatsApp nor receiving notifications:

How is that even possible?

Update on July 26th: Someone on Reddit told me that notifications trigger an app’s activity in background. When I disable WhatsApp’s notifications, it stoped being active as in the screenshot abot.